Phase 1 of this research will include the enrollment of 30 severely obese subjects at the UW (15 at UCSD). Subjects will be asked to complete two consecutive MRE exams with inter-exam repositioning, at a single research visit on either a 1.5T or 3T MRI scanner. The order of each scan will be randomly assigned. Each MRE exam will last approximately 30 minutes and require periodic 15-20 second breath-holds. Subjects will be able to take a short break prior to being repositioned for the second exam.
Specific aims include:
1. Optimize magnetic resonance elastography (MRE) wavefield generation in severely obese adults, applicable to both 2D- and 3D-MRE methods.
2. Characterize the precision profile of conventional 2D-MRE and advanced multiparametric 3D-MRE in severely obese adults by determining a) same-day repeatability, b) field-strength reproducibility, c) reader reproducibility, and d) between-day reproducibility.
3. Determine the accuracy of conventional 2D- and advanced 3D-MRE in severely obese adults using paired liver biopsies as the reference, to a) diagnose fibrosis and NASH cross-sectionally and b) monitor change in fibrosis and resolution of NASH longitudinally.